Complementary metal-oxide semiconductor (CMOS) integrated circuits frequently include wells formed in the substrate. CMOS integrated circuits include n-channel transistors formed in the substrate and p-channel transistors formed in the wells, or vice versa.
Integrated circuits can include bipolar transistors instead of or in addition to CMOS transistors. Frequently, these integrated circuits also include wells formed in the substrate. The bipolar transistors can include NPN transistors formed in the substrate and PNP transistors formed in the wells, or vice versa.
Parasitic diodes and parasitic transistors can form in integrated circuits that include wells. Proper biasing of the wells is required to limit the harmful effects of these parasitic diodes and parasitic transistors.
The present invention may address one or more of the above issues.